Re: replay pause vs. standby promotion

On 2020/03/20 15:22, Atsushi Torikoshi wrote:
>
> On Fri, Mar 6, 2020 at 10:18 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com <mailto:masao(dot)fujii(at)oss(dot)nttdata(dot)com>> wrote:
>
>
> OK, so patch attached.
>
> This patch causes, if a promotion is triggered while recovery is paused,
> the paused state to end and a promotion to continue. OTOH, this patch
> makes pg_wal_replay_pause() and _resume() throw an error if it's executed
> while a promotion is ongoing.
>
> Regarding recovery_target_action, if the recovery target is reached
> while a promotion is ongoing, "pause" setting will act the same as "promote",
> i.e., recovery will finish and the server will start to accept connections.
>
> To implement the above, I added new shared varible indicating whether
> a promotion is triggered or not. Only startup process can update this shared
> variable. Other processes like read-only backends can check whether
> promotion is ongoing, via this variable.
>
> I added new function PromoteIsTriggered() that returns true if a promotion
> is triggered. Since the name of this function and the existing function
> IsPromoteTriggered() are confusingly similar, I changed the name of
> IsPromoteTriggered() to IsPromoteSignaled, as more appropriate name.
>
>
> I've confirmed the patch works as you described above.
> And I also poked around it a little bit but found no problems.

Thanks for the review!
Barrying any objection, I will commit the patch.

Regards,

--
Fujii Masao
NTT DATA CORPORATION
Advanced Platform Technology Group
Research and Development Headquarters